Microscopes are known, for example, from WO 2007/144197 A1. The focusing module there can comprise the control unit, a second detector and first focusing optics, and can be switchable into a focus-hold mode, in which an intensity-modulated object is imaged into the sample via the first focusing optics and the objective, and an image of the imaged object is recorded by means of the second detector and, in addition, the control unit holds the focus position of the objective on the set focus position, on the basis of the recording of the second detector.
In the case of such a microscope, although it is possible to focus deeply into the sample, in this case it is no longer possible to implement the focus-hold mode of the focusing module, since the image of the imaged object is no longer incident on the second detector.